Journal of School of Public Health and

  Background and Aim: Xylanases are widely used in various food industries, including livestock and poultry feed industries, the pulp and paper industry, as well as the pharmaceutical industry. Several strains of microorganisms are capable of producing this enzyme by different mechanisms, Bacilliaceae being one of its important sources at the commercial scale. The culture medium for xylan is expensive and, therefore, it is not economical to use in producing xylanase by Bacillus subtilis S7e. The purpose of this study was to explore the possibility of using industrial-agricultural wastes as a source of carbon and nitrogen in submerged fermentation, for producing xylanase in amounts higher than that which can be produced by xylan culture (10048 U/).

  Materials and methods: The indigenous strain of Bacillus subtilis S7e was cultured in the xylan medium, followed by incubation at 30°, 37° and 40° C. Then the nitrogen sources (rapeseed meal, soybean meal, tomato seeds, tea seeds, peptone, Vinas alcohol, casein, and ammonium sulfate) and carbon sources (molasses, wheat bran, rice bran, rice industry waste, gluten waste, malt waste, whey powder, and bagasse) were substituted for the meat and yeast extracts and the xylan culture medium, respectively.

  Results : The maximum enzyme activity was observed at 30° C after 48 hours of incubation (6183U/l). Rapeseed meal with an enzyme activity of 10048U/l and molasses with an enzyme activity of 3759U/l were found to be the best nitrogen and carbon sources for Bacillus subtilis S7e , respectively.

  Conclusion: Based on the findings of this study, f rom an economic point of view, agricultural-industrial wastes (rapeseed meal and molasses) are an excellent substitute for the more expensive culture media currently in use for producing the enzyme xylanase.

Background and Aim: The petroleum contamination is one of the inevitable consequences of population increase and energy consumption. In this study, the method of Bioremediation and Bacillus bacteria have been used in order to remove the petroleum contamination.

Material and Methods: The samples of soil were collected and the bacteria were isolated and identified.Then, the production of Biosurfactant, the rate of naphthalene degradation and appropriate growth conditions of them were examined.

Results: The Bacillus sp. included Bacillus cereus, Paenibacillus lactis, Bacillus fusiformis and Bacillus subtilis. The pure cultures and consortium have surface tension values less than 40 mN/m. Therefore, they were considered biosurfactant producers. The consortium had the tolerance ability of naphthalene up to 1000ppm.The appropriate conditions for the growth of Bacillus consortium was pH equal to 6, shaker rate 150 rpm, nitrogen source of Yeast extract and the concentration of naphthalene equal to 200ppm.

Conclusion: Bacillus consortium had more ability compared to single strains for reducing the surface tension, production of Biosurfactant, growth in culture media containing naphthalene and its degradation. It has indicated in several of the similar researches that Bacillus consortium or other bacteria have more ability in Biodegradation of organic contaminants.

Background and Aim: Chlorpyrifos is an organophosphate pesticide used in agriculture for pest control. It is a relatively persistent poison and an environmental pollutant with adverse effects on human health. This study was conducted to isolate and characterize chlorpyrifos-degrading bacteria from rice field soils in Amol City, Iran.

Materials and Methods: In this experimental study, soil samples were collected from rice fields with a history of toxic pollution. A minimal salt broth (Msb) medium containing 100 mg/l chlorpyrifos as the carbon and energy source was used for isolating pesticide-degrading bacteria. The colonies were characterized by Gram staining and biochemical tests and sequencing was done using the PCR method.

Results: Four chlorpyrifos-degrading bacterial strains were isolated from the soils. They included Bacillus licheniformis strain IARI-M-12, Bacillus pumilus strain MS42, Bacillus cereus strain ESB15, and Delftia tsuruhatensis strain SJ113. The effects of temperature and pH on the bacterial strains were investigated. The Bacillus strains showed the fastest growth at a temperature of 35^o C and a pH=7 in a Msb medium containing chlorpyrifos.

Conclusion: The results of this study demonstrate that bacteria in the farmland can degrade the chlorpyrifos poison. Thus, these bacteria can be used to reduce the environmental problems resulting from soil contamination with chlorpyrifos in the ecosystem.